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/**
* FreeRDP: A Remote Desktop Protocol Implementation
* Transport Packets (TPKTs)
*
* Copyright 2011 Marc-Andre Moreau <marcandre.moreau@gmail.com>
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include <freerdp/config.h>
#include "tpdu.h"
#include "tpkt.h"
#include <winpr/wlog.h>
#define TAG FREERDP_TAG("core.tpkt")
/**
* TPKTs are defined in:
*
* http://tools.ietf.org/html/rfc1006/
* RFC 1006 - ISO Transport Service on top of the TCP
*
* http://www.itu.int/rec/T-REC-T.123/
* ITU-T T.123 (01/2007) - Network-specific data protocol stacks for multimedia conferencing
*
* TPKT Header
* ____________________ byte
* | |
* | 3 (version) | 1
* |____________________|
* | |
* | Reserved | 2
* |____________________|
* | |
* | Length (MSB) | 3
* |____________________|
* | |
* | Length (LSB) | 4
* |____________________|
* | |
* | X.224 TPDU | 5 - ?
* ....
*
* A TPKT header is of fixed length 4, and the following X.224 TPDU is at least three bytes long.
* Therefore, the minimum TPKT length is 7, and the maximum TPKT length is 65535. Because the TPKT
* length includes the TPKT header (4 bytes), the maximum X.224 TPDU length is 65531.
*/
/**
* Verify if a packet has valid TPKT header.
*
* @param s A stream to read from
*
* @return \b TRUE for success, \b FALSE otherwise
*/
int tpkt_verify_header(wStream* s)
{
BYTE version = 0;
if (!Stream_CheckAndLogRequiredLength(TAG, s, 1))
return -1;
Stream_Peek_UINT8(s, version);
if (version == 3)
return 1;
else
return 0;
}
/**
* Read a TPKT header.
*
* @param s A stream to read from
* @param length A pointer to the result, must not be NULL
*
* @return \b TRUE for success, \b FALSE otherwise
*/
BOOL tpkt_read_header(wStream* s, UINT16* length)
{
BYTE version = 0;
if (!Stream_CheckAndLogRequiredLength(TAG, s, 1))
return FALSE;
Stream_Peek_UINT8(s, version);
if (version == 3)
{
UINT16 len = 0;
if (!Stream_CheckAndLogRequiredLength(TAG, s, 4))
return FALSE;
Stream_Seek(s, 2);
Stream_Read_UINT16_BE(s, len);
/* ITU-T Rec. T.123 8 Packet header to delimit data units in an octet stream */
if (len < 7)
{
WLog_ERR(TAG, "TPKT header too short, require minimum of 7 bytes, got %" PRId16, len);
return FALSE;
}
if (!Stream_CheckAndLogRequiredLength(TAG, s, len - 4))
{
WLog_ERR(TAG, "TPKT header length %" PRIu16 ", but received less", len);
return FALSE;
}
*length = len;
}
else
{
/* not a TPKT header */
*length = 0;
}
return TRUE;
}
BOOL tpkt_ensure_stream_consumed_(wStream* s, size_t length, const char* fkt)
{
if (length > UINT16_MAX)
{
WLog_ERR(TAG, "[%s] length %" PRIuz " > %" PRIu16, fkt, length, UINT16_MAX);
return FALSE;
}
size_t rem = Stream_GetRemainingLength(s);
if (rem > 0)
{
WLog_ERR(TAG,
"[%s] Received invalid TPKT header length %" PRIu16 ", %" PRIdz " bytes too long!",
fkt, length, rem);
return FALSE;
}
return TRUE;
}
/**
* Write a TPKT header.
*
* @param s A stream to write to
* @param length The value to write
*
* @return \b TRUE for success, \b FALSE otherwise
*/
BOOL tpkt_write_header(wStream* s, UINT16 length)
{
if (!Stream_CheckAndLogRequiredCapacity(TAG, (s), 4))
return FALSE;
Stream_Write_UINT8(s, 3); /* version */
Stream_Write_UINT8(s, 0); /* reserved */
Stream_Write_UINT16_BE(s, length); /* length */
return TRUE;
}
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